新型Janus膜的制备及其在高盐含油废水膜蒸馏处理中的应用

采用表面蚀刻-电喷雾协同技术制备了具有微/纳凹槽表面结构的亲水/疏水型Janus膜,并系统考察了Janus膜的脱盐性能及耐润湿、抗污染功能。Janus膜具有水相超疏油的性能,对原油、正己烷、甲苯和汽油的水下油接触角分别为152.7°、150.1°、146.7°和151.1°。直接接触式膜蒸馏应用实验表明：在连续50 h的运行过程中,Janus膜对盐的截留率可达100%、膜通量稳定在10.18 kg·(m²·h)⁻¹;对于不同浓度(0.1、0.2和0.3 mmol·L⁻¹等)的十二烷基硫酸钠,Janus膜均表现出优异的抗润湿效果。在处理高盐含油废水过程中,Janus膜未发生膜润湿和膜污染的现象,膜通量及盐截留率也保持稳定;油滴力学探针测试结果定量阐释了Janus膜强健的抗油污能力。制备的新型Janus膜兼具耐润湿与抗污染特性,拓展了膜蒸馏技术在高浓度难降解废水处理领域的应用。     

Enhanced sorption of perfluorooctane sulfonate (PFOS) on carbon nanotube-filled electrospun nanofibrous membranes

Multi-walled carbon nanotube-filled electrospun nanofibrous membranes (MWCNT-ENFMs) were prepared by electrospinning. The addition of MWCNTs (0.5 wt.% vs. ENFMs) doubled the specific surface area and tensile strength of the ENFMs. The MWCNT-ENFMs were used to adsorb perfluorooctane sulfonate (PFOS) in aqueous solutions. The sorption kinetics results showed that the sorption rate of PFOS onto the MWCNT-ENFMs was much higher than the sorption rate of PFOS onto the pure ENFMs control, and the pseudo-second-order model (PSOM) described the sorption kinetics well. The sorption isotherms indicated that the sorption capacity of the MWCNT-ENFMs for PFOS (16.29 ± 0.26 μmol g⁻¹) increased approximately 18 times, compared with the pure ENFMs (0.92 ± 0.06 μmol g⁻¹). Moreover, the solution pH significantly affected the sorption efficiency and sorption mechanism. The MWCNT-ENFMs were negatively charged from pH 2.0–10.0, but the electrostatic repulsion between the MWCNT-ENFMs and PFOS was overcome by the hydrophobic interactions between PFOS and the MWCNTs or nanofibers. The strong hydrophobic interactions between PFOS and the MWCNTs played a dominant role in the sorption process. For the pure ENFMs, the electrostatic repulsion was conquered by the hydrophobic interactions between PFOS and the nanofibers at pH > 3.1. In addition to the hydrophobic interactions, an electrostatic attraction between PFOS and the pure ENFMs was involved in the sorption process at pH < 3.1.     

膜蒸馏处理糖精钠生产废水

采用直接接触式膜蒸馏(DCMD)工艺处理糖精钠生产废水。分析了经过活性炭吸附预处理前后,膜蒸馏连续循环运行的效果。实验结果表明,未经预处理的废水在膜蒸馏过程中,废水中所含有机物不仅导致膜材料的润湿,引起产水电导率升高及膜孔润湿,促进盐晶体在膜表面附着,使产水通量下降。经吸附预处理后,膜蒸馏过程中产水通量介于10.40～11.24 kg/(m2.h)。吸附预处理能有效减缓产水通量的衰减,提高产水水质。废水经过活性炭预处理后进行膜蒸馏浓缩处理,当浓缩倍数达到5倍时,通量保持在10.55 kg/(m2.h)左右;产水水质稳定,截留率在99.5%以上。研究结果表明,吸附-膜蒸馏工艺可以应用于糖精钠生产废水的回用处理,有明显的应用前景。     

膜蒸馏去除水中砷的研究

采用新型膜蒸馏技术对水中As（III）与As（Ⅴ）的去除展开了研究。实验结果表明,膜蒸馏对水中As (III)及As (Ⅴ)具有较高的去除能力：当产水中砷含量超过10 μg/L时,原水中As (III)与As (Ⅴ)的浓度可分别高达40 mg/L和2 000 mg/L。局部润湿现象的存在导致As (III)及As (Ⅴ)跨膜至产水侧,PVDF微孔膜在溶液中的负电性以及As (III)与 As (Ⅴ)在溶液中存在形式的不同导致膜蒸馏对两者去除能力的差异。360 h连续运行过程中产水通量及电导率稳定,且整个过程中As (III)均低于检测限,说明PVDF微孔膜具有良好的疏水性和稳定的除砷性能。     

真空膜蒸馏和膜吸收及其集成工艺处理高氨氮废水

采用PP中空纤维膜组件,对VMD(真空膜蒸馏)和MA(膜吸收)脱氨过程进行了研究。考察了料液pH值(9.0~11.0)、料液进口温度(20~50℃)对脱氨效率的影响。研究结果表明,VMD和MA脱除率分别达85%和99%以上。料液pH和料液进口温度对VMD脱氨效果的影响较大,提高料液pH和进口温度可以明显提高VMD的脱氨效率;料液pH对MA的脱氨效率影响较为显著。对2种膜工艺进行了技术集成,利用该集成工艺可达到99.96%以上的氨去除率,出水可达标排放,并且可以有效防止硫酸铵的二次污染。     

叠式空气隙膜蒸馏组件膜污染实验研究

采用一种具有旋流结构的多层层叠式空气隙膜蒸馏膜组件,以20 g/L氯化钠盐水为热工质,考察在70℃条件下膜污染情况,实验结果表明,一个周期的连续运行和间歇性操作膜表面在高温下较快进入膜污染,8个周期后膜通量下降为初始通量的42%。膜表面有大量黄色附着物,电镜SEM分析显示,膜表面被不均匀堆积的颗粒状污染物及长方体结晶物覆盖,能谱EDS分析,污染物有极少量NaCl结晶的Na、Cl元素,还有O、C、Mg、Cu和Fe等元素。污染膜经5%盐酸溶液清洗后无机垢沉淀被去除,表观效果较好。     

PTFE中空纤维膜直接接触式膜蒸馏过程抗污染性能

通过研究不同原水对直接接触式膜蒸馏过程的影响,考察了聚四氟乙烯膜对无机盐、胶体和有机物的抗污染性能。研究表明,在35 g/L氯化钠溶液的4倍浓缩过程中,PTFE膜的相对通量降低至0.72;与碳酸钙饱和溶液的浓缩过程相比,由于溶解度的差异,硫酸钙饱和溶液浓缩过程中晶体析出量更多,通量衰减也更为严重;浓缩硅溶胶时,二氧化硅单体聚合并吸附于膜面从而引起膜通量的衰减,随着浓缩的进行,料液pH值不断上升,使得胶体体系愈加稳定,浓缩到2.6倍后相对通量没有随着浓缩倍数的增加出现明显下降,维持在0.73左右;腐殖酸在水中表现出的亲水性和电负性使其难以在具有较强疏水性的聚四氟乙烯膜表面上形成滤饼层,浓缩过程中相对通量始终保持在0.9以上。     

Removal of arsenic from contaminated groundwater by solar-driven membrane distillation

Experimental investigations were carried out on removal of arsenic from contaminated groundwater by employing a new flat-sheet cross flow membrane module fitted with a hydrophobic polyvinylidenefluoride (PVDF) microfiltration membrane. The new design of the solar-driven membrane module in direct contact membrane distillation (DCMD) configuration successfully produced almost 100 per cent arsenic-free water from contaminated groundwater in a largely fouling-free operation while permitting high fluxes under reduced temperature polarization. For a feed flow rate of 0.120 m³/h, the 0.13 μm PVDF membrane yielded a high flux of 74 kg/(m² h) at a feed water temperature of 40 °C and, 95 kg/m² h at a feed water temperature of 60 °C. The encouraging results show that the design could be effectively exploited in the vast arsenic-affected rural areas of South-East Asian countries blessed with abundant sunlight particularly during the critical dry season.     

Recent advances in the application of silica nanostructures for highly improved water treatment: a review

The demand for high-quality safe and clean water supply has revolutionized water treatment technologies and become a most focused subject of environmental science. Water contamination generally marks the presence of numerous toxic and harmful substances. These contaminants such as heavy metals, organic and inorganic pollutants, oil wastes, and chemical dyes are discharged from various industrial effluents and domestic wastes. Among several water treatment technologies, the utilization of silica nanostructures has received considerable attention due to their stability, sustainability, and cost-effective properties. As such, this review outlines the latest innovative approaches for synthesis and application of silica nanostructures in water treatment, apart from exploring the gaps that limit their large-scale industrial application. In addition, future challenges for improved water remediation and water quality technologies are keenly discussed.

     

多效膜蒸馏技术浓缩回收废水中的二甲基亚砜

利用具有内部潜热回收功能的气隙式多效膜蒸馏(MEMD)组件对含二甲基亚砜(DMSO)的化纤废水进行了浓缩回收研究,考察了料液中DMSO浓度、进料流量、进料温度和膜侧进口温度对膜通量、造水比、分离因子和回收率的影响。结果表明,多效膜蒸馏可以将DMSO废水浓缩至200~300 g/L;初始浓度为6.2 g/L时,造水比和分离因子最高值分别为12.4和76.0;虽然膜通量、造水比和分离因子均随料液浓度增大而下降,但是当DMSO浓度达到200 g/L时,膜通量、造水比、分离因子仍分别高达3.74 L/(m2·h)、7.1、32.1;在整个浓缩过程中,回收率维持在99.6%以上;当DMSO废水浓缩达到150 g/L以上时,含有少量DMSO的渗透液可作为二次料液继续用MEMD过程浓缩。膜组件在连续运行的1个月内保持了良好的操作性能。该实验研究表明,多效膜蒸馏过程可以高效节能地浓缩回收化纤废水中的DMSO。     

The time of concentration application in studies around the world: a review

Environmental Science and Pollution Research - The time of concentration (Tc) is the main hydrological parameter used to characterize the response of a given Hydrological Response Unit (HRU) to a...     

膜蒸馏处理页岩气井压裂返排液

页岩气压裂返排液的有效处理是页岩气开发急需解决的关键环保问题之一。针对新页HF-1井页岩气压裂返排液经预氧化结合湿式氧化（PO-WAO）工艺处理的出水COD不达标、含盐量高等技术难题,采用膜蒸馏处理技术对工艺的出水进行深度处理。通过膜蒸馏单因素和正交实验表明料液温度和冷凝温度对膜蒸馏处理效果影响较大,在料液温度、冷凝液温度、真空度、运行时间分别为80℃、8℃、0.090 MPa和60 min的最佳工艺条件下,膜通量可达1.750 L·（m2·h）-1,出水COD浓度为95.8 mg·L-1,出水水质可满足《污水综合排放标准》（GB 8978-1996）中一级排放的要求。膜蒸馏出水中电导率为63 μS·cm-1,氯化钠的质量浓度为1.168 0 mg·L-1,可有效降低处理后的压裂废液对周围土壤的盐碱化伤害。     

直接接触式膜蒸馏工艺处理高浓度氨氮模拟废水中操作条件的影响

采用直接接触式膜蒸馏处理高浓度氨氮模拟废水。实验对初始pH值、原料液流量和渗透液流量等3项操作条件进行了比较研究。结果表明,提高原料液的初始pH值可以大幅度地提高氨氮的去除效率、传质系数和分离效率,当初始pH达到12时,30 min内氨氮去除率可达到98%以上;提高料液流量可以得到同样的规律,当初始pH值为11,料液流量由400 L/h提高至800 L/h时,氨氮去除率由79.8%提高至88%;但渗透液流量的提高对处理效果的影响并不明显。     

水消毒处理中膜技术的应用

本文较全面地评述了膜技术在水消毒处理中的应用 ,包括消毒机理、效果及影响因素 ,展望了应用前景     

Fluoride removal from aqueous solution by direct contact membrane distillation: theoretical and experimental studies

Direct contact membrane distillation (DCMD) process using polyvinylidene fluoride (PVDF) membrane was used for fluoride removal from aqueous solution. This study has been carried out on heat and mass transfer analyses in DCMD. The dusty-gas model was used to analyze the mass transfer mechanism and to calculate the permeate flux. The heat transfer is analyzed based on energy balance, and the different layers are considered as a series of thermal resistances. Mass transfer analysis showed that the transition Knudsen-molecular diffusion is the dominant mechanism to describe the transport of water vapor through the pores of the PVDF membrane. The most significant operating parameter is the feed temperature. The permeate increases sensitively with feed temperature and velocity, and it shows insignificant change with feed salts concentration. Heat transfer analysis showed the conduction through the matrix of the membrane presents the major part of available energy. The increasing feed temperature leads to increase thermal efficiency (TE) and decrease temperature polarization coefficient (TPC). The experimental results are in good agreement with theoretical values. Therefore, it is suggested to work at high feed temperature, which will benefit both the thermal efficiency and permeate flux. The experimental results proved that DCMD process is able to produce almost fluoride-free water suitable for many beneficial uses.     

直接接触式膜蒸馏浓缩处理高浓度发酵废液效能

采用直接接触式膜蒸馏工艺(DCMD)浓缩处理高浓度发酵废液,在热侧温度65℃、冷侧温度30℃条件下,连续运行21 h,考察了浓缩过程中产水通量、产水侧COD和TOC浓度变化及蛋白质浓缩效果.结果表明,产水通量随运行时间延长而下降且降速较快,15 h内由17.1 kg/(m2·h)降至8.9 kg/(m2·h);经去离子水冲洗,产水通量可恢复至56.1%.产水中COD和TOC浓度随处理时间延长而不断增大.此外,原水与膜蒸馏出水中GC-MS分析结果也表明,随运行时间延长,原水中有更多种类的有机物进入产水侧,主要为挥发性有机物.对膜内表面进行扫描电镜-能谱(SEM-EDS)分析发现,膜内表面有块状沉积物出现,主要成分为有机物,含有少量的无机物.DCMD运行21 h后,废液体积浓缩8.3倍,有用组分蛋白质浓缩6.9倍,COD和TOC的去除率均达95%以上.     

Correction to: The time of concentration application in studies around the world: a review

Environmental Science and Pollution Research -     

道南膜技术测定自由态重金属离子研究

土壤和水体中自由态重金属离子由于具有生物有效性和毒性而一直受到广泛关注。近年来发展起来的道南膜技术(DMT)对待测体系干扰小、测定范围广且能同时测定多种重金属离子,得到较广泛的应用。当前,DMT已较成熟,已有实验室道南膜技术(lab-DMT)和原位道南膜技术(filed-DMT),广泛应用于土壤溶液、地表水以及人工配制的络合溶液,已成功测定的重金属离子包括Cu2+、Zn2+、Pb2+、Cd2+、Al3+、Ni2+和Cr(Ⅲ);已开发出基于离子跨膜迁移动力学DMT,解决了重金属离子达到平衡时间过长和重金属离子低于电感耦合等离子-质谱检测限等问题。详细介绍了DMT的原理、方法、应用及离子跨膜传输机制,将关于DMT的研究分为适用性和改进研究、理论基础研究、应用研究3类分别进行综述;提出了采样装置微型化、发展实时动态的原位测定技术、改进原位测定技术用于淹水土壤、湿地及底泥中自由态重金属离子的测定是该技术的发展方向。     

Heterogeneous water phase catalysis as an environmental application: a review

Catalytic water phase processes as an environmental application is a relatively novel subject with tremendous potential in the near future. This review of 120 references presents the wide scale of heterogeneous water phase applications studied mainly within past five years. Both oxidation and hydrogenation processes are included as well as TiO₂ assisted photocatalysis. According to the references, heterogeneous catalysis is developing rapidly. New bimetallic catalysts and supports with higher surface area have improved catalytic efficiency in both oxidation and hydrogenation processes. It also seems that study on use of some waste materials such as red mud as catalyst is a very progressive field. On the whole, the chemical aspects are pretty well known, but the catalyst durability, and in many cases activity as well, has to be improved.     

减压膜蒸馏法处理石煤提钒废水

利用减压膜蒸馏设备处理石煤提钒废水,分别比较了废水经预处理前后,料液温度、流量、渗透侧真空度等操作条件对膜通量和截留率的影响。测定了不同浓缩倍数情况下膜通量的变化。实验表明,进料温度升高会使膜通量增加,温度为65℃时,热效率最高为70．1％。提高料液流量或真空度都会使膜通量增加。废水经VMD处理产出的淡水电导率均在10μS／cm以下,脱盐率可达99．98％以上。在温度为70％、流量为60L／h、真空度为0．095MPa时,石煤提钒废水经预处理后的废水膜通量为11．359kg／（m^2·h）,浓缩10倍时,膜通量仍有3．185kg／（m^2·h）。